Preheat the oven to 350° F. Line an 8X8 baking pan with aluminum foil. In a large bowl, combine the ricotta, corn, egg, 1/4 cup Parmesan, parsley, and nutmeg. Stir and season with salt and pepper. In a blender or with an immersion stick blender in a bowl, puree the tomatoes, onion and garlic.

Place 1/2 cup of the sauce at the bottom of the baking pan, spreading it evenly to coat. Layer the zucchini slices on top of the sauce, overlapping the edges. Add half the ricotta mixture and top with the mushrooms. Spread the rest of the ricotta on top. Place another layer of zucchini and top with the remaining sauce. Sprinkle with mozzarella and remaining Parmesan.

Baked uncovered, 40 to 45 minutes until the cheese is bubbly and lasagna is brown around the edges. Allow to cool 5 to 10 minutes before serving. Cool completely before storing refrigerated, in an air-tight container for up to three days.